Help solve this TPMS mystery

T

twa318

Member
I'm trying to wrap my brain around whats going on with my TPMS and hopefully someone will be able to chime and and help me figure out what is going on.

Shortly after I passed 200k miles I had the blinking TPMS light go off. Took it to my local NTB and they confirmed it was a single sensor with a bad battery that needed to be replaced for $65.

They replaced the sensor with a new one but were having trouble resetting the TPMS light. They were eventually able to reset the light, but a solid TPMS light came on as soon as I pulled in my driveway 10 miles later. I checked all 5 tire pressures and they were fine.

So I take it back the next day, and they tell me the first diagnostic was incorrect and that there is a second sensor that has gone bad and needs replacing. At that point I said just put the old sensor back and refund my money and I'll just simply bypass the system.

Well they put the old sensor back in, refunded my money, reset the system, and its been almost 500 miles and 14 days later and still no TPMS light has come back on.

Is it possible to bypass the TPMS through software? Could they have possibly done this? Why would the system flash a blinking light, then a solid light, then no light with the same exact sensors in place and same PSI?
 
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I am still new to the TPMS game but here is how I understand it…

You can either buy sensors with a fixed RFID which require you to re-learn / program into the car using the OBDII port… or buy programmable sensors and clone the existing sensor RFID which does not require any modification on the vehicle side.

I suspect if your truck was re-programmed, you might be missing a sensor from inventory causing the issues you are seeing.
 
TPMS sensor batteries typically last 10 years, all 5 typically need to be replaced at the same time. Use Denso sensors, (or Dill).

When one sensor is replaced, all 5 sensor IDs need to be uploaded to the ECU.
(or Did they clone the bad sensor ID?)

It's really Not that complicated..

I check my tire pressure with my TPMS scanner without loosening a valve cap. :baby:
 
Short answer is no, it is not possible through software alone. Solid light is low pressure. Blinking indicates a miscommunication, which will flash for a minute or two then stay solid. Doesn't necessarily mean its bad/dead.
I have experienced the flashing light a couple times in the past month. Started on a 3500 mile road trip but I figured it was due to the large temperature fluctuations, as every check pressure was unchanged.
Should still look into the bypass or replacing.
 
The 4Runner must have known I was talking about it, because the solid light came back on this morning.

Verified that all 5 tire Psi was still correct. No idea what’s going on but I’m going to do the bypass via jumpering the two with a small gauge wire and be done with it for good.
 
TPMS is a weird thing. I was a Costco Tire Center Mgr for 13years, and I’ve seen TPMS do weird and unexplainable things. My own 07 4R has OEM sensors still working, but I can’t explain how I drove around for a month without my spare in the car, and it never noticed?

I know that many times, we scan all 4, find a dead one, replace it, then another shows up dead at the relearn process. I assume the relearn eats up some battery life, so if you’re at 5% remaining on a sensor that didn’t show as dead, that relearn is often the final nail in the coffin. That is why we almost always recommend replacing all at once. It would be so nice if the sensors some how showed remaining battery, but they do not. Makes us seem like liars, but we’re not...

Toyota’s are by far the trickiest, followed by Push-button start Fords and some Chevys that display the psis.
 
I'd bet the sensor they installed isnt being picked up.

Anecdotally, I had a spare that was perpetually flat, and left it at my house a few days while I went to work. when that sensor was out of range, the light illuminated solidly, and that behavior should be the same if the sensor is dead, or the sensor they replaced is still programmed and the new sensor is not.

if you're a tech savvy person, it is possible to get Toyota's Techstream so you can see/edit the TPMS sensor IDs yourself. Then you could either leave out the sensor that was removed by the shop (leaving one tire unable to report), provide the new ID (assuming it's compatible and you know the ID) or any number of other possibilities.

Bypassing with software I guess might be possible this way, I dont know what happens if you intentionally "unlearn" all of the sensors.

My recommendation would be to do the hardware bypass, but wire in a switch so you can turn it off/on at will. It's a really easy job, and you can hide the switch in the glovebox.
 
gfluff said:
TPMS is a weird thing. I was a Costco Tire Center Mgr for 13years, and I’ve seen TPMS do weird and unexplainable things. My own 07 4R has OEM sensors still working, but I can’t explain how I drove around for a month without my spare in the car, and it never noticed?

I know that many times, we scan all 4, find a dead one, replace it, then another shows up dead at the relearn process. I assume the relearn eats up some battery life, so if you’re at 5% remaining on a sensor that didn’t show as dead, that relearn is often the final nail in the coffin. That is why we almost always recommend replacing all at once. It would be so nice if the sensors some how showed remaining battery, but they do not. Makes us seem like liars, but we’re not...

Toyota’s are by far the trickiest, followed by Push-button start Fords and some Chevys that display the psis.
Click to expand...

Fascinating post from someone with 13 years of experience, I appreciate your insight about the relearning process eating up the remaining battery life.

I'm chalking this TPMS mystery to exactly what you described, weird and unexplainable.

After resetting the system and verifying all 5 tire pressures at the beginning of the month, the TPMS light went out, only to come back on solid a few days later. I was getting ready to bypass the system when I decided to check all tire pressure again, turns out I have a slow leak in the rear tire and it was indeed low. Have been keeping it inflated to correct psi and.....the light went out!

The TPMS lights been out for three weeks now, after flashing for weeks with two supposedly dead sensors.

Completely bizarre, but its clearly functioning properly again. As you said, weird and unexplainable.
 
Typically, Toyota/Denso TPMS sensors last 10+ years, best to replace all the TPMS sensors when you are due for new tires around that time frame, so the wheel does not need to be broken down to just to update the TPMS sensors. :pray2:

Some models have 5 sensors.

People, it's really not that complicated... :spider:

Once the new TPMS sensors are installed the serial numbers need to be uploaded to the ECU, takes maybe 3 mins.
 
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